Pitch block



June 5, 1956 HlLslNGER 2,748,548

PITCH BLOCK Filed April 6. 1954 IN VEN TOR.

AT'I'OR N EYS United States Patent PITCH BLOCK Arthur R. Hilsinger, Mount Tabor, N. J., assignor to Sadler Bros., Inc., a corporation of Massachusetts Application April 6, 1954, Serial No. 421,378

4 Claims. (Cl. 51-216) This invention relates to a pitch block for use in retaining a lens for grinding the same.

Heretofore, pitch blocks have been notched so that a gauge could be used to obtain the dimension of the lens from time to time as grinding progressed. The pitch used to retain the lens on the block must be scraped away at the location of the notch in order that the gauge may be applied, and it is a rather messy operation to scrape this pitch, which is usually done with the fingernails of the users hand in order to accomplish this.

One of the objects of this invention is to provide a guide for the gauging notches of the pitch block so that the pitch will be directed away from the notch, thus making removal of the pitch for gauging purposes unnecessary.

Another object of the invention is to provide a ridge or guide integral with the pitch block and at such a location as not to interfere with the use of the pitch block and yet perform the desirable function of maintaining the gauging notch free from pitch so that the gauging may be accomplished without scratching the pitch from the lens.

Another object of the invention is to provide a device which may be applied either to concave or convex pitch blocks.

With these and other objects in view, the invention consists of certain novel features of construction as will be more fully described and particularly pointed out in the appended claims.

In the accompanying drawings:

Figure 1 is a sectional view illustrating a lens mounting on a concave pitch block against a grinding wheel;

Figure 2 is a plan view of the concave pitch block showing the face upon which the pitch is positioned;

Figure 3 is a plan view of the back of the pitch block;

Figure 4 is a sectional view of a convex type of pitch block;

Figure 5 is a plan view thereof.

In proceeding with this invention, I have built a ridge about each gauging notch of the pitch block so that the pitch which holds the lens on the block will not squeeze down into the notches when the lens is pressed into position on the block, rather the pitch will be directed away from the notch, thus leaving this notch free for gauging the pitch block without the need of scraping the pitch from the location of the notch.

2,748,548 Patented June 5, 1956 With reference to the drawings, 10 designates generally a concave pitch block having a generally circular peripheral edge 11 with gauging notches 12, 12, 12, and 12 therein through which a gauge may be applied to a lens. The pitch 13 which covers the block and which secures the lens 14 thereto usually oozes out into these notches 12 as it is pressed tightly upon the pitch block, and after grinding occurs of the face of the lens, this pitch must be scraped from the area of the notch in the block so that a gauge instrument may be properly applied.

In this disclosre, however, ridges 15 are formed around the edge 16 of each of the notches 12 and are built up sufiiciently so that the pitch is directed at either side of the notch 12 rather than into the notch and thus the notch is left free for applying a gauge to the lens Without the necessity of scraping the pitch 13 from the area of the notch.

In the showing in Figures l-3, the center portion 17 of the body of the block is concave for the reception of the convex surface of a lens. However, the ridges 15 are of a height less than would contact a plane which would extend from the intermediate portions 18--18 between the notches, as may be best seen in Figure 1 where a plane 19 is there shown in dot dash lines.

In order to manipulate the block in the grinding operation, the body has a projection 20 with recesses 23 therein for reception of a center 24 or other securing means to hold the block in the desired position in the grinding operation against the abrasive tool 27.

In Figures 4 and 5 a block designated generally 25 is identical in all respects to the block above described except that the center portion 26 is convex instead of concave as is the center portion 17 in the form shown above. The notches 12 are the same, and the ridges 15 about these notches are the same as in the form first described.

I claim:

1. A pitch block for a lens comprising a body with gauging notches in its edge and an integral ridge along the marginal edge of each notch to direct the pitch away from the notch.

2. A pitch block as in claim 1 wherein the body inwardly of the notches is concave.

3. A pitch block as in claim 1 wherein the body inwardly of the notches is concave and the ridge is sufiiciently high so that it forms a Wall to prevent the pitch flowing out of said motors.

4. A pitch block as in claim 1 wherein the body inwardly of the notches is convex.

References Cited in the file of this patent UNITED STATES PATENTS 1,538,651 Pellow May 19, 1925 1,643,978 Bugbee Oct. 4, 1927 1,952,373 Hill Mar. 27, 1934 2,151,509 Goddu Mar. 21, 1939 2,224,168 Tillyer Dec. 10, 1940 2,603,922 McCarthy July 22, 1952 

